Rotor Member Thrust Member Stress Concentration

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Solution Overview

Problem

The existing rotor members in synchronous motors face stress concentration issues due to centrifugal forces, leading to reduced maximum revolution speed and torque output, as the cylindrical member's tension is unevenly distributed during press-fitting, causing friction and stress on the magnet segments' corner portions.

Innovation Solution

Incorporating a thrust member that pushes the cylindrical member against the sleeve part between adjacent magnet segments, distributing the stress evenly and preventing local curvature, thus mitigating stress concentration and allowing for higher tension uniformity and increased revolution speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the cylindrical member is uniformly stretched to increase holding strength, then the maximum revolution speed is improved, but stress concentration occurs at the corner-shaped portion of the magnet segments

Engineering Contradiction:

Improveholding strength of cylindrical memberVSAvoidstress concentration on magnet segment corners

Core Design Contradiction:

StrengthVSStress or pressure

Solution Approach 1:

The patent applies local quality by creating a recess portion in the cylindrical member at the location corresponding to the corner-shaped portion of the magnet segments. This local structural modification redistributes the stress that would otherwise concentrate at the corner, allowing the cylindrical member to maintain uniform tension while preventing stress concentration points. The recess portion acts as a stress-relief feature that preserves the overall holding strength while protecting the magnet segment corners.

Inventive Principle:

Principle #3Local quality

2Reliability

If the cylindrical member is stretched to prevent magnet segments from flying off, then the reliability is improved, but the cylindrical member abuts against the corner-shaped portion causing friction and stress

Engineering Contradiction:

Improveprevention of magnet segment detachmentVSAvoidfriction and stress from abutting

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the problematic corner-shaped portion of the magnet segment by creating a recess portion in the cylindrical member that accommodates this feature. By removing or accommodating the protruding corner portion through the recess, the abutting contact between the cylindrical member and magnet segment corners is eliminated. This prevents the harmful friction and stress while maintaining the reliability of magnet segment retention through the overall cylindrical structure.

Inventive Principle:

Principle #2Taking out (Extraction)

3Speed

If the cylindrical member is tensioned to increase holding strength, then the maximum revolution speed is improved, but the stress distribution becomes uneven

Engineering Contradiction:

Improvemaximum revolution speedVSAvoiduneven stress distribution

Core Design Contradiction:

SpeedVSStress or pressure

Solution Approach 1:

The patent applies local quality by introducing a recess portion at the specific location where stress concentration would occur due to the corner-shaped magnet segment portion. This localized structural feature creates a more uniform stress distribution throughout the cylindrical member when tension is applied, enabling the member to withstand higher tensions required for increased revolution speed without developing uneven stress patterns that would lead to failure.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration enhances the rotor's maximum revolution speed and torque output while preventing magnet segment detachment, improving the motor's reliability and durability by evenly distributing the stress across the cylindrical member.

Implementation Method 1

a thrust member 330 that thrusts the cylindrical member 321 to the outer side in the radial direction against the sleeve part 301 is present between a plurality of the magnet segments 311 which are adjacent in the circumferential direction

Methodology Applied

Scientific EffectForce distribution: Mechanical Force

Implementation Method 2

it is necessary to raise the holding strength (retaining force) of the cylindrical member serving as the magnet retaining member of the rotor outer circumference in order to prevent the magnet segments from flying off due to centrifugal force

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 3

tensile strength is increased by increasing the stretch of the cylindrical member, thereby raising the holding strength of the magnet segments

Methodology Applied

Scientific EffectPress-fitting: Mechanical Force

Data Source

PatentUS10340757B2Rotor member, rotor and electric motor

Publication Date: 2019.07.02 FANUC LTD

AI summary

To provide a rotor member, rotor, and electric motor equipped with the same, which suppress the stress or stretching concentrated on a part of a cylindrical member, thereby enabling to raise the maximum revolution speed, and enabling greater torque to be obtained. In a rotor member fixed by press-fitting to a rotary shaft part of a rotating electrical machine, a thrust member that thrusts a cylindrical member to an outer side in the radial direction against a sleeve part is present between a plurality of magnet segments which are adjacent in the circumferential direction.